Oscillation generation



Oct. 13, 1936. L. USSELMAN 2,057,170

OSCILLATION GENERATION Filed Oct. 7 1932 2 Sheets-Sheet 1 x N Q E Q INVENTOR- GEORGE L. USSELMAN ORNEY- Patented Oct. 13, 1936' UNITED STATES PATENT OFFICE OSCILLATION GENERATION poration of Delaware Application October 'I, 1932, Serial No. 636,710

' 18 Claims. (Cl. 250-36) It has been proposed, for frequency control, to couple the end of a transmission line inductively or capacitively to the plate or output circuit of an electron discharge device generator and the other end of the transmission line to the grid or grids of the generator. The length of the line was adjusted so that the phase of the energy when it arrived at the grid was such as to produce maximum stability of frequency.

As the above method of coupling the line to the generator does not lend itself so well to ultra high frequency practice, the object of my present invention is to provide a suitable frequency controlling circuit for an ultra short wave generator,

which however, takes advantage of long line phenomena but avoids the coupling dimculties mentioned. To fulfill this object, I provide a space wave pick-up circuit in combination with a transmission line for controlling the frequency of the electric generator of very short waves or oscillations. In brief, I propose to pick up, at some distance away, some of the radiated energy from the generator and to transmit it back to the grids or control electrodes of the generator to control the frequency thereof.

That is, my present scheme, using the space wave pick-up, is more suitedfor feeding energy I I shall explain my invention more fully hereinafter with the aid of the accompanying drawings,

wherein, y

Figure 1 diagrammatically indicates a short wave system utilizing the combination of a space 40 wave pick-up and a long transmission line, a plurality of half wave lengths long at a desired operating frequency for frequency control;

Figure 2 is a top plan view of Figure 1 having in addition a reflector for the radiating antenna; and, n

'F'igure 3 illustrates a further modification of my present invention.

Referring to Figure 1 E is the glass envelope inside of which are the tube elements. The gas inside the envelope may be of any; element and any pressure but preferably it should be of very low pressure ordinarily spoken of as a vacuum;

A1A1'and AzAzconstitute the anode-antenna to the center of which is connected the anode ourrent supply lead B. Positive plate potential is radiation pick-up unit P1 and P2.

maintained through this lead by an outside powersource. The tube anodes A1 and A: are welded to the anode antenna in the position as illustrated.

These are thin metal cylinders, located coaxially with relation to each other and are welded on each 5 side. of the center of 'the anode antenna whose axis is parallel with that of the cylinders. There is a V space between the inner ends of the tube anodes A: and A: where the leads enter and connect to the internal elements. 0

Inside of the anodes are the screen grids 8G1 and 8G2. The two screen grids are joined at the center and a third arm X of it extends out over the leads, and clamps on the glass envelope for support. The control grids CG1 and CG: are 15 located inside the screen grids. The control grids do not join at the center and each has a separate lead. It should be mentioned here that the screen grids have a common bias lead Y. Inside of each. control grid is mounted the filament F1 and F2. The filaments may be connected in parallel or in series. Preferably they should have a common pair of leads FF.

The screen grid lead is connected to each filament lead by means of the by-pass condensers C. The long lines L1 and Li a plurality of half wave lengths long at a desired operating frequency, are connected to control grid leads CG1 and C62. The long lines have uniformly distributed inductance and capacity and are arranged close together or concentrically to prevent radiation.

The other end of the lines is shorted by the bar 8. Negative bias voltage is supplied through the center point of this bar and through the long lines to the control grids. The pick-up wires P1 and P2 may be connected to the lines L1 and L: any dis- 35 tance from the bar up to one-quarter of the operatlng wave length. The coils C1 and C: are for adjusting the tuning of P1 and P: to the radiated wave. The pick-up wires should be parallel to the anode antenna. Figure 2 shows the position of the parabolic reflector R in relation to the anode antenna and the pick-up wires.

In operation, the generator of Figures 1 and 2 .is similar to thatoi' a pushpull oscillator. When the generator is oscillating the function of the 45 space wave pick-up and long line is as follows: The energy (of ultra high frequency) is radiated from the anode antenna A1A1 and AzAa. The reflector R will direct the beam along the lines L1 and La to the end of which is connected the 50 Some of this radiated energy causes high frequency current and voltage to be set up in the pick-up wires P1 and P1. This energy is transmitted to the u lines L1 and L: which in turn transmit it back to the generator control grids CGI and CG:. By properly adjusting the distance of the pick-up wires PlP2 from the anode antenna A1A1A2A2 and by properly adjusting the length of the long lines L1 and Lathe phase of the energy arriving over the long line to the control grids can be made to aid and maintain the oscillations in the generator anode antenna.

The phase relation of grid voltage will'be approximately 180' degrees from that of the plate voltage for a range of high frequencies. For ultra high frequency work the phase of the grid voltage will have to be in advance of 180 degrees to compensate for the time required for the elec+ trons to reach the anode, i. e. the electrons must reach the anode when it is minimum positiv potential.

The amount of energy picked up on P1 and P2 may be regulated by adjusting the length of P1 and P2. The tuning of the pick-up may be maintained by adjustment of coils C1 and C2.

The approximate frequency to be maintained will depend on the length of the anode antenna.

It should be approximately half (in length) of the operating wave length. The exact adjustment will be made by adjusting the length of the long line Lr-Lz and the distance between the pick-up wires and the. generator antenna. The operation of the space wave and long line combination is similar to the long line method of frequency control described by James L. Finch and-James W. Conklin in their United States Patent No. 1,945,545, and. by Clarence W. Hansell in his United States Patent No. 1,945,546, both granted February 6, 1934.- This combination will function to maintain constant frequency because any small change in frequency' of the generator will cause a large change in the phase relation between the anode voltage and the energy returning to the grids from the pick-up wires and the long line. It would also be difiicult for the generator to change its frequency because the grids are controlled by the energy which has been already radiated. If the pick-up wires are placed several wave lengths away from the generator antenna then the pick-up arrangement cannot be directly affected by induction or capacity from the generator. The pick-up arrangement which I have shown is only for illustration of the principles involved and may consist ofa more elaborate arrangement for performing the above function.

A modification of my present invention is shown in Figure'3 wherein a diiferent form of generator is utilized. The anode A is approximately a half wave doublet or linear radiator. This is connected at the center to a positive voltage supply lead B. 'I'he. central portion of the doublet anode and part of the lead B is sur-.

rounded by a shield D on which is maintained a negative bias voltage. Outside the shield and spaced a short distance each side of the center of the anode are two filaments F1 and E3. Connected to F1 are two transmission lines L1, and to Ft are connected two other lines L2. The ends of these long lines'are connected to the filament transformer T. The shorting bar S serves to adjust the length of the long'line L1-Lz. The bar S is, in this case, only capacitively coupled to the lines to prevent short circuiting of the filament supply. The capacity between conductive plate S and the lines is such as to constitute an effective short circuit at the operating frequencies. thereby maintaining the line at S at a voltage nodal point. The pick-up arrangement P1Pz C1'C2 serves the" same purpose which is discussed in connection with Figure 1.

The tube elements are enclosed in the glass envelope E, the inside of which has a gas at very low pressure. The entire apparatus functions about the same as the scheme described in Figure 1, except that the phase of the filaments in relation to the anode may be somewhat different. In general, the filaments operate pushpull in potential and if the filament on one side is maximum negative the anode potential on the same side will be maximum positive. Conditions on the opposite side of the tube will be just the reverse. Due to the ultra high frequency at which this generator will operate, and due to the comparatively low velocity of the electrons the phase of thefilaments will have to be" advanced ahead of that which ordinarily obtains in lower frequency oscillators. There will be some anode to filament capacity feed-back. This would ordinarily be degenerative but it can be made to regenerate by proper adjustbine to form L1 and the other two filament power supply conductors combine to form L2. The portion of the shield D between the filaments and anodes A may be of mesh or perforated construction.

Having thus described my invention, what I claim is: 1. Anoscillatory system comprising an elecron discharge device having an anode, a cathode and a control electrode, means for causing said device to generate oscillations. a radiating circuit coupled to said electrodes, a space wave pickup antenna spaced from said radiating circuit and picking up energy radiated from said circuit, and an unbroken, long linear transmission line comprising wires which are closely spaced to one another directly connected between said pick-up antenna and said electron discharge device for feeding energy picked up by said pickup antenna to electrodes of said device thereby controlling the frequency of operation thereof, such line having a predetermined length greater than the length of the wave generated by said system and such as 'to produce frequency stability.

2. An oscillatory system comprising an electron discharge device having an output electrode, means for causing said device ttrgenerate oscillations, a radiator connected to said output electrode, an antenna spaced from said radiator and picking upenergy radiated therefrom, and a long substantially radiationless transmission line comprising .wires which are closely spaced to one another directly connected between said pick-up antenna and said electron discharge device for feeding to said device the energy picked up to stabilize the frequency of operation of said device, said line having a length equal to a multiple of half the length of the generated wave.

3. An oscillatory system comprising an electron discharge device having an anode, a cathode and a control electrode, means for causing said device to generate oscillations, a linear radiator connected to said anode, a pick-up antenna,

a spaced from said radiator and picking up energy radiated therefrom, and a two-wire, linear, un-

brokenftransmission line directly connected between said pick-up antenna and said control electrode for feeding back the picked up energy as frequency stabilizing energy, to said control electo control electrode feed back through the interelectrode capacity existing between the anode and control electrode.

5. An oscillatory system comprising an electron discharge device having an anode, a cathode and a control electrode, means for causing said device to generate oscillations, a radiating antenna coupled to said anode, a pick-up antenna picking up energy radiated from said antenna,

and along linear unbroken transmission linedirectly connected to said cathode and extending to said pick-up antenna for applying tosaid cathode the energ." picked up in such a way as to stabilize, duet'o the length of said line, the *frequency of oscillations generated by said device and radiated by said radiating antenna.

6. An oscillatory system comprising a pair of anodes, a pair of cathodes, and a pair of control electrodes all within a single envelope, a radiating element coupled to said anodes, a pick-up unit picking up energy from said element and spaced therefrom, and a long transmission line a plurality of half wave lengths'long coupled to said pick-up unit and said control electrodes for stabilizing the frequency of operation of said systems.

7. An oscillatory system comprising a pair of anodes and a pair of control electrodes all within a single envelope. a radiating element coupled to said anodes for radiating oscillatory energy generated by said anodes and said control electrodes, a pick-up unit spaced from said radiating antenna, and a feedback path comprising a long transmission line, a plurality of half wave lengths long at a desired operating frequency connected between said pick-up unit and said control electrodes for feeding back a portion of the radiated energy to said control electrodes whereby the frequency of oscillations generated by said system is stabilized.

8. An oscillating system comprising an elecpick-up tron discharge device having within an evacuated container a plurality of anodes, cathodes and control electrodes. a linear radiator connected in phase opposition to said anodes, a two-wire, linear, unbroken transmission'llne a plurality of half wave lengths long connected to said-control electrodes, and a pick-up unit spaced from said radiator picking up energy radiated 'by said radiator, said pick-up unit being coupled to said transmission line in such a way as to produce standing waves thereon whereby said oscillatory system is caused to oscillate at a substantially constant frequency determined in main by the spacing between said radiating antenna and unit and the length of said transmission line.

9. High frequency'apparatus comprising 9, hermedcslly sealed container.'a metallic cylindrical element within said container, a cathode arranged at each end of said cylindrical element, a linear member serving as an anode arranged within said cylindrical element, means for maintaining said anode at a positive potential with respect to said cathodes, and means for maintaining said cylindrical element at a negative potential with respect to said cathodes.

10. Apparatus as claimed in the preceding claim, characterized by the fact that a high frequency circuit is connected to said cathode.

11. High frequency apparatus comprising a hermetically sealed container, a metallic substantially cylindrical element within said container, a cathode arranged externally of and at each end of said cylindrical element, a linear member serving asan anode arranged within said cylindrical element, means for maintaining said anode at a positive potential with respect to said cathodes, and means for maintaining said cylindrical element at a negativepotential with respect to said cathodes.

12. High frequency apparatus comprising a hermetically sealed container, a metallic cylindrical element within said container, a cathode arranged externally of and at each end of said cylindrical element, a source of energy for heating said cathodes, and a two-wire transmission line individual to each cathodeconnecting each cathode to said source, a linear anode member arranged within said cylindrical element, extending outside said container and functioning to radiate energy, and an antenna spaced away from said container for collecting energy radiated by said linear member, said' antenna having two sion line and the other arm to the other transmission line whereby the collected energy is applied to said cathodes for stabilizing the frequency 'of oscillations produced by said high frequency apparatus.

13. Apparatus in accordance with claim 12 including a tuning element capacitively coupled to the wires of both said transmission lines for adjusting the effective length of said lines.

14. An oscillatory system comprising an electron discharge device having an output electrode, means for causing said device to generate oscillations, a radiator connected to said output electrode, an antenna parallel to said radiator and spaced therefrom for picking up energy radiated thereby, a long, substantially radiationless transmission line, a plurality of half wave lengths long at the frequency of the generated oscillations comprising wires which are closely spaced to one another connected between said pick-up antenna and said electron discharge device for feeding to said device the energy picked up to stabilize the frequency of operation of said device, and a parabolic reflector surrounding at least part of .said oscillatory system for directing the energy radiated thereby toward said pick-up antenna.

15. An oscillatory system comprising an electron discharge device having an anode, cathode. and control electrode, means for causing said device to generate oscillations, a radiating circuit coupled to said electrodes, a wave pick-up antenna spaced from said radiating circuit and picking up energy radiated from said circuit, and a long, two-wire transmission line, a plurality of half wave lengths long at the frequency of the generated oscillations connected between said pick-up antenna and said oscillation generator for feeding energy by said pick-up antenna to the electrodes of said oscillation generator, thereby controlling the frequency of operation thereof, and a strap bridging the'wires' of said twowire line at the end of said line remote from said oscillation generator for short circuiting said line a; for radio frequency energy, said pick-up antenna comprising a pair of arms, each arm being coupled to a difierent wire of said line.

16. An oscillatory system ,comprising an electron discharge device having an anode, cathode, lo: and control electrode, means for causing said device to generate oscillations, a radiating circuit coupled to said electrodes, a wave pick-up antenna spaced from said radiating circuit and picking up energy radiated from said circuit,

15 anda long, two-wire transmission line, a plurality of half wave lengths long at the frequency of "the generated oscillations connected between saidpick-up antenna and-said oscillation gen erator for feeding energy by said pick-up an- 20... tenna to the electrodes of said oscillation generator, thereby controlling the frequency of operation thereof, and a strap bridging the-wires of said two-wire lineat the end of saidline remote from said oscillation generator for short circuiting said 25. line forradio frequency energy, said pick-up anteima comprising a pair of arms, each am being r coupled to a diiferent wire of said line, and a tuning coilin each of said arms for tuning said antenna. 30: '17; An oscillatory system comprising an electron discharge device having an anode, cathode, and control electrode, a radiating circuit coupled to said electrodes, a wave pick-up antenna spaced from said radiating circuit and picking up energy radiated from said circuit, and a long, two-wire transmission line connected between said pick-up antenna and said oscillation generator for feeding energy picked-up by said antenna to the electrodes of said oscillation generator, thereby controlling the frequency of operation thereof, and a strap bridging the wires of said two wire line at a portion of said line remote from said oscillation generator for short circuiting said line for radio frequency energy, said pick-up antenna comprising a pair of arms coupled to said line at points less than one-quarter of the length of the operating wave from said strap, each arm being coupled to a different wire of said line.

18. High frequency apparatus comprising a hermetically sealed container, a metallic cylindrical element within said container, a cathode'arranged at each end of said cylindrical element, a

linear member substantially one-half wave lon at the operating frequency serving as an anode arranged within said cylindrical element, means for maintaining said anode at a positive potential with respect to said cathodes, and means for maintaining said cylindrical element at a negative potential with respect to said cathodes.

' GEORGE L. USSELMAN. 

